[HIP] Add Kokkos for versions >= 4.2.00 (#214)

It uses whichever CXX/C compiler is passed to the LLVM test suite as
CMAKE_CXX_COMPILER or CMAKE_C_COMPILER to compile kokkos.

The inclusion of kokkos to build and test is enabled via CMake flag
EXTERNAL_HIP_TESTS_KOKKOS=ON.

Version tag can be given via EXTERNAL_HIP_TESTS_KOKKOS_TAG to specify
the specific tag that the system should use to download, build, and test.
If not specified otherwise the version will default to 4.5.01 (currently
most recent version available).

Author: jplehr

External/HIP/CMakeLists.txt

@@ -1,3 +1,5 @@
+include(ExternalProject)
+
 include(External)
 include(GPUTestVariant)
 llvm_externals_find(TEST_SUITE_HIP_ROOT "hip" "HIP prerequisites")
@@ -121,6 +123,27 @@ macro(create_hip_tests)
     create_hip_test(${_HIP_Suffix})
   endforeach()
 
+  if (EXTERNAL_HIP_TESTS_KOKKOS)
+    set(EXTERNAL_HIP_TESTS_KOKKOS_TAG "4.5.01" CACHE STRING "Kokkos tag to download and test")
+    ExternalProject_Add(TestKokkosHIP
+      GIT_REPOSITORY  https://github.com/kokkos/kokkos.git
+      GIT_TAG         ${EXTERNAL_HIP_TESTS_KOKKOS_TAG}
+      CMAKE_ARGS      -DCMAKE_BUILD_TYPE=Release
+                      -DCMAKE_CXX_STANDARD=17
+                      -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+                      -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+                      -DKokkos_ENABLE_HIP=ON
+                      -DKokkos_ARCH_AMD_GFX90A=ON
+                      -DCMAKE_PREFIX_PATH=/opt/rocm
+                      -DKokkos_ENABLE_TESTS=ON
+      INSTALL_COMMAND ""
+      TEST_COMMAND    ""
+      )
+    add_custom_target(build-kokkos DEPENDS TestKokkosHIP)
+    ExternalProject_Get_Property(TestKokkosHIP BINARY_DIR)
+    add_custom_target(test-kokkos COMMAND "ctest" WORKING_DIRECTORY "${BINARY_DIR}" DEPENDS build-kokkos)
+  endif()
+
   add_custom_target(hip-tests-all DEPENDS hip-tests-simple
     COMMENT "Build all HIP tests.")